I think you need to understand how a tune is applied, to understand the answer.
How it works is, you don't actually get the source code of the ECU. Tuners usually find a way to dump the code, reverse engineer it to figure out where parameters can be changed. So when they apply a tune, its basically just settings that they change to give you that "tune" that they would have tweaked after testing multiple different variations.
Thats one way, to change the settings. Another way is obviously something that sits inbetween, interpret values from sensors and the ecu, and then change it on the fly to let the engine do different things, or give it that tune.
Either way, there isn't a stamp on anything that says I have applied Tinuva's super duper boost v2.1 tune.
Finding physical changes are usually much easier than finding what tune is on there. It would mean, someone needs copies of all tunes made ever for your car, dump your cars current tune and compare it to all the templates out there to find a match.
So in short, its not impossible but damn near it. Its easier to just apply another tune over the current one if you want to know what is on there.